This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Chronic Obstructive Pulmonary Disease (COPD) is a disease of the lungs that affects many smokers. Patients with COPD are at increased risk for bacterial infections including those caused by a kind of bacteria named Streptococcus pneumoniae (Pneumococcus). Pneumococcus can cause pneumonia, meningitis, infections of the blood, or COPD [unreadable]exacerbations[unreadable], a temporary worsening of lung symptoms that may require hospitalization and could be life-threatening. At present, most public health organizations recommend that all patients with COPD, as well as anybody over the age of 65, be vaccinated against pneumococcus. The vaccine currently used in adults is the capsular polysaccharide (CPS) vaccine which is made from 23 types of killed pneumococcus. There are almost 100 types of pneumococcus but these 23 are the most common causes of infections in adults. Giving the vaccine causes the body to make antibodies that help fight off pneumococcal infections caused by these 23 types of pneumococcus. Although the vaccine has been shown to prevent infections in young, healthy patients, it appears to be less effective in older patients and in those with underlying medical problems such as COPD. In the last several years, a new vaccine called the protein-conjugate vaccine (PCV) has been developed. Like the CPS vaccine, the PCV is also made from killed pneumococcus but it also contains diphtheria toxin, a substance that appears to increase the body[unreadable]s immune response. The vaccine has been used in children under the age of 2 since the year 2000 and has undergone testing in adults. Although the PCV is made from only 7 types of pneumococcus and therefore does not offer protection against as many bacteria as the CPS vaccine, some studies in patients over age 70 suggest that the antibody response to the PCV vaccine may be better than with the CPS vaccine. The Food and Drug Administration approved dose of the PCV vaccine in children is 0.5 mL but it appears that a 1.0 mL dose may work better in adults. In this study, we will try to find out whether 1.0 mL of the PCV vaccine gives a better immune response than the CPS vaccine in patients with moderate to severe COPD. The study is funded by The National Institutes of Health and is conducted by Dr. Steven Scharf from the University of Maryland School of Medicine and researchers from nine other research institutions in the United States. We plan to enroll about 18 patients at the University of Maryland, and 180 patients nationally.